DE102012112060A1 - Preparing metal formate, useful e.g. as setting accelerator, comprises reacting formic acid amine adduct with metal hydroxide e.g. sodium hydroxide to obtain two-phase mixture containing tertiary amine compound, metal formate and water - Google Patents

Abstract

Preparing at least one metal formate consisting of sodium formate, potassium formate, magnesium formate, calcium formate or aluminum formate comprises (a) providing a formic acid amine adduct (A2), (b) reacting (A2) with at least one metal hydroxide consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide or aluminum hydroxide in the presence of water to obtain at least two-phase mixture containing an upper phase (O3) comprising the tertiary amine compound of formula (NR1R2R3) (A1) and a lower phase (U3) comprising a metal formate and water. Preparing at least one metal formate consisting of sodium formate, potassium formate, magnesium formate, calcium formate or aluminum formate comprises (a) providing a formic acid amine adduct of formula (NR1R2R3 xi(HCOOH)) (A2), (b) reacting (A2) with at least one metal hydroxide consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide or aluminum hydroxide in the presence of water to obtain at least two-phase mixture containing an upper phase (O3) comprising the tertiary amine compound of formula (NR1R2R3) (A1) and a lower phase (U3) comprising a metal formate and water. R1-R3 : unbranched or branched, acyclic or cyclic, aliphatic, araliphatic or aryl 1-6C-organic group, where individual carbon atoms are optionally substituted by a hetero group comprising O or N and two or all three of R1-R3 are connected to each other to form a chain with at least 4 atom; and xi : 0.4-5.

Description

The present invention relates to a process for the preparation of metal formates by reacting a formic acid-amine adduct with metal hydroxides.

Metal formates are versatile value products. Sodium and potassium formate are used, for example, as surface deicing agents for roads and airports. Sodium formate is used to produce oxalic acid. Aluminum and sodium formate are used in textile and leather processing ( Industrial Organic Chemistry, Hans-Juergen Arpe, WILEY-VCH Verlag GMBH & Co. KGaA, Weinheim 2007; ISBN 978-3-527-31540-6, pages 48 and 232-235 ). Calcium formate is used as an auxiliary in the tannery, as a setting accelerator for cementitious building materials, as auxiliaries for the processing of oil emulsions, for the production of silage auxiliaries and as an additive for animal nutrition.

Potassium formate is formed as an intermediate in the formate-potash process for the production of potassium carbonate. Sodium and calcium formate are by-produced in the preparation of polyols such as pentaerythritol, neopentyl glycol and trimethylolpropane. The recovery of metal formates via the formate-potash process or via the production of polyols is disadvantageous since these processes use the toxic C _{1 building} block carbon monoxide.

In addition, metal formates can be prepared by direct homogeneous-catalyzed hydrogenation of carbon dioxide in the presence of bases ( Chem. Rev. 1995, 95, 259-272 ). In addition, metal formates are accessible by homogeneously catalyzed hydrogenation of carbonate and bicarbonate salts. As homogeneous catalysts, catalysts with the noble metals Ru, Pd, Rh, and Ir are used as the metal component.

In homogeneous-catalyzed hydrogenation, however, the problem arises that the separation of the homogeneous catalyst from the reaction mixture is extremely difficult.

The object of the present invention is to provide a process for the preparation of metal formates which does not have the disadvantages of the prior art described above or only to a significantly reduced extent. The synthesis of the metal formate is said to do without the toxic C ₁ -Baustein carbon monoxide. In addition, the separation of the metal formates from the reaction mixture should be simplified compared to the methods described in the prior art.

• (a) Bereitstellung eines Ameisensäure-Amin-Addukts der allgemeinen Formel (A2) NR¹R²R³*x_i HCOOH (A2), in der x_i im Bereich von 0,4 bis 5 liegt und R¹, R², R³ unabhängig voneinander einen unverzweigten oder verzweigten, acyclischen oder cyclischen, aliphatischen, araliphatischen oder aromatischen Rest mit jeweils 1 bis 16 Kohlenstoffatomen darstellen, wobei einzelne Kohlenstoffatome unabhängig voneinander auch durch eine Heterogruppe ausgewählt aus den Gruppen -O- und >N- substituiert sein können sowie zwei oder alle drei Reste unter Bildung einer mindestens jeweils vier Atome umfassenden Kette auch miteinander verbunden sein können, und
• (b) Umsetzen des Ameisensäure-Amin-Addukts (A2) in Gegenwart von Wasser mit mindestens einem Metallhydroxid ausgewählt aus der Gruppe bestehend aus Natriumhydroxid, Kaliumhydroxid, Magnesiumhydroxid, Calciumhydroxid und Aluminiumhydroxid unter Erhalt eines mindestens zweiphasigen Gemischs (MF) enthaltend eine Oberphase (O3), die das entsprechende tertiäre Amin der allgemeinen Formel (A1) enthält NR¹R²R³ (A1), in der R¹, R², R³ die vorstehend genannten Bedeutungen haben, und einer Unterphase (U3), die das entsprechende mindestens eine Metallformiat und Wasser enthält.

The object is achieved by a process for the preparation of at least one metal formate selected from the group consisting of sodium formate, potassium formate, magnesium formate, calcium formate and aluminum formate comprising the steps

• (a) Preparation of a Formic Acid-Amine Adduct of General Formula (A2) NR ¹ R ² R ³ * x _i HCOOH (A2), in which x _{i is} in the range of 0.4 to 5 and R ¹ , R ² , R ³ independently represent an unbranched or branched, acyclic or cyclic, aliphatic, araliphatic or aromatic radical each having 1 to 16 carbon atoms, wherein individual carbon atoms independently of one another may also be substituted by a hetero group selected from the groups -O- and> N-, and two or all three radicals may also be linked together to form a chain comprising at least four atoms each, and
• (B) reacting the formic acid-amine adduct (A2) in the presence of water with at least one metal hydroxide selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and aluminum hydroxide to obtain an at least two-phase mixture (MF) containing an upper phase (O3 ) containing the corresponding tertiary amine of general formula (A1) NR ¹ R ² R ³ (A1), in which R ¹ , R ² , R ^{3 have} the meanings given above, and a lower phase (U3) containing the corresponding at least one metal formate and water.

The terms "step" and "process step" are used synonymously below.

Providing the formic acid-amine adduct (A2); Process step (a)

The formic acid-amine adducts (A2) can be prepared in various ways, for example (i) by direct reaction of the tertiary amine (A1) with formic acid, (ii) by hydrolysis of methyl formate to formic acid in the presence of the tertiary amine (A1 ), (iii) by catalytic hydration of carbon monoxide in the presence of the tertiary amine (A1) or (iv) by hydrogenation of carbon dioxide to formic acid in the presence of the tertiary amine (A1). The latter method of catalytic hydrogenation of carbon dioxide has the particular advantage that carbon dioxide is available in large quantities and is flexible in its source.

The preparation of the formic acid-amine adduct (A2) according to step (a) is preferably carried out by homogeneously catalyzed reaction of carbon dioxide with hydrogen in the presence of a tertiary amine (A1) and at least one polar solvent selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol and water.

• (a1) homogen-katalysiertes Umsetzen eines Reaktionsgemischs (Rg) enthaltend Kohlendioxid, Wasserstoff, mindestens ein polares Lösungsmittel ausgewählt aus der Gruppe bestehend aus Methanol, Ethanol, 1-Propanol, 2-Propanol, 1-Butanol, 2-Butanol, 2-Methyl-1-propanol und Wasser sowie ein tertiäres Amin (A1) NR¹R²R³ (A1) in Gegenwart mindestens eines Komplexkatalysators, der mindestens ein Element ausgewählt aus den Gruppen 8, 9 und 10 des Periodensystems enthält, in einem Hydrierreaktor unter Erhalt, gegebenenfalls nach Zugabe von Wasser, eines zweiphasigen Hydriergemischs (H) enthaltend eine Oberphase (O1), die den mindestens einen Komplexkatalysator und das tertiäre Amin (A1) enthält, und eine Unterphase (U1), die das mindestens eine polare Lösungsmittel, Reste des mindestens einen Komplexkatalysators sowie das Ameisensäure-Amin-Addukt (A2) enthält, NR¹R²R³*x_iHCOOH (A2),
• (a2) Phasentrennung des in Schritt (a1) erhaltenen Hydriergemischs (H) in einer ersten Phasentrennvorrichtung in die Oberphase (O1) und die Unterphase (U1) und Extraktion der Reste des mindestens einen Komplexkatalysators aus der Unterphase (U1) in einer Extraktionseinheit mit einem Extraktionsmittel enthaltend das tertiäre Amin (A1) unter Erhalt eines Raffinats (R2) enthaltend das Ameisensäure-Amin-Addukt (A2) und das mindestens eine polare Lösungsmittel und eines Extrakts (E2) enthaltend das tertiäre Amin (A1) und die Reste des mindestens einen Komplexkatalysators.

In a preferred embodiment, the preparation of the formic acid-amine adduct (A2) comprises the steps

• (a1) homogeneously catalyzed reaction of a reaction mixture (Rg) comprising carbon dioxide, hydrogen, at least one polar solvent selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl 1-propanol and water and a tertiary amine (A1) NR ¹ R ² R ³ (A1) in the presence of at least one complex catalyst containing at least one element selected from Groups 8, 9 and 10 of the Periodic Table, in a hydrogenation reactor to obtain, optionally after addition of water, a biphasic hydrogenation mixture (H) containing an upper phase (O1) containing the at least one complex catalyst and the tertiary amine (A1), and a lower phase (U1) containing the at least one polar solvent, residues of the at least one complex catalyst and the formic acid-amine adduct (A2), NR ¹ R ² R ³ * x _i HCOOH (A2),
• (a2) phase separation of the hydrogenation mixture (H) obtained in step (a1) in a first phase separation device in the upper phase (O1) and the lower phase (U1) and extraction of the residues of the at least one complex catalyst from the lower phase (U1) in an extraction unit with a Extraction agent comprising the tertiary amine (A1) to obtain a raffinate (R2) containing the formic acid-amine adduct (A2) and the at least one polar solvent and an extract (E2) containing the tertiary amine (A1) and the radicals of the at least one complex catalyst.

In a preferred embodiment, the provision of the formic acid-amine adduct (A2) according to step (a) thus comprises steps (a1) and (a2). The formic acid-amine adduct (A2) contained in the raffinate (R2) is subsequently admixed, according to step (b), with at least one metal hydroxide selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and aluminum hydroxide to give the corresponding metal formate (s). implemented.

Preparation of the hydrogenation mixture (H); Process step (a1)

In the process according to the invention, a reaction mixture (Rg) which comprises carbon dioxide, hydrogen, at least one complex catalyst comprising at least one element selected from groups 8, 9 and 10 of the Periodic Table, at least one polar solvent selected from the group is reacted in process step (a1) Group consisting of methanol, ethanol, 1-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol and water and a tertiary amine (A1).

The carbon dioxide used in process step (a1) can be solid, liquid or gaseous. It is also possible to use gas mixtures containing large quantities of carbon dioxide, provided they are substantially free of carbon monoxide (volume fraction of <1% CO). The hydrogen used in the hydrogenation of carbon dioxide in process step (a1) is generally gaseous. Carbon dioxide and hydrogen may also contain inert gases, such as nitrogen or noble gases. However, their content is advantageously below 10 mol%, based on the total amount of carbon dioxide and hydrogen in the hydrogenation reactor. While larger amounts may also be tolerable, they generally require the use of a higher pressure in the reactor, requiring further compression energy.

Carbon dioxide and hydrogen can be fed to process stage (a1) as separate streams. It is also possible to use a mixture containing carbon dioxide and hydrogen in process step (a1).

In the process according to the invention, a tertiary amine (A1) is used in process step (a1) in the hydrogenation of carbon dioxide. In the context of the present invention, "tertiary amine (A1)" is understood as meaning both one (1) tertiary amine (A1) and mixtures of two or more tertiary amines (A1).

The tertiary amine (A1) used in the process according to the invention is preferably selected or matched with the polar solvent such that the hydrogenation mixture (H) obtained in process step (a1) is at least biphasic, if appropriate after the addition of water. The hydrogenation mixture (H) contains an upper phase (O1) which contains the complex catalyst and the tertiary amine (A1), and a lower phase (U1) which contains the polar solvent, residues of the complex catalyst and a formic acid-amine adduct (A2) ,

The tertiary amine (A1) should be enriched in the upper phase (O1), i. the upper phase (O1) should contain the major part of the tertiary amine (A1). In the context of the present invention, by "enriched" or "main part" with respect to the tertiary amine (A1) is a weight fraction of the free tertiary amine (A1) in the upper phase (O1) of> 50% based on the total weight of the free tertiary Amine (A1) in the liquid phases, ie the upper phase (O1) and the lower phase (U1) in the hydrogenation mixture (H) to understand.

By free tertiary amine (A1) is meant the tertiary amine (A1) which is not bound in the form of the formic acid-amine adduct (A2).

The weight fraction of the free tertiary amine (A1) in the upper phase (O1) is preferably> 70%, in particular> 90%, in each case based on the total weight of the free tertiary amine (A1) in the upper phase (O1) and the lower phase ( U1) in the hydrogenation mixture (H).

In addition, non-polar solvents such as aliphatic, aromatic or araliphatic solvents may be added to the tertiary amine (A1). Preferred non-polar solvents are, for example, octane, toluene and / or xylenes (o-xylene, m-xylene, p-xylene).

The preferred tertiary amine to be used in the process according to the invention is an amine of the general formula NR ¹ R ² R ³ (A1) in which the radicals R ¹ , R ² , R ^{3 are} identical or different and independently of one another represent an unbranched or branched, acyclic or cyclic, aliphatic, araliphatic or aromatic radical having in each case 1 to 16 carbon atoms, preferably 1 to 12 carbon atoms, where individual carbon atoms independently of one another may also be substituted by a hetero group selected from the groups -O- and> N-, and two or all three radicals may also be linked together to form a chain comprising at least four atoms each. In a particularly preferred embodiment, a tertiary amine of the general formula (A1) is used, with the proviso that the total number of carbon atoms is at least 3.

• • Trimethylamin, Triethylamin, Tri-n-propylamin, Tri-n-butylamin, Tri-n-pentylamin, Tri-n-hexylamin, Tri-n-heptylamin, Tri-n-octylamin, Tri-n-nonylamin, Tri-n-decylamin, Tri-n-undecylamin, Tri-n-dodecylamin, Tri-n-tridecylamin, Tri-n-tetradecylamin, Tri-n-pentadecylamin, Tri-n-hexadecylamin, Tri-(2-ethylhexyl)amin.
• • Dimethyl-decylamin, Dimethyl-dodecylamin, Dimethyl-tetradecylamin, Ethyl-di-(2-propyl)amin, Dioctyl-methylamin, Dihexyl-methylamin.
• • Tricyclopentylamin, Tricyclohexylamin, Tricycloheptylamin, Tricyclooctylamin und deren durch eine oder mehrere Methyl-, Ethyl-, 1-Propy-, 2-Propyl-, 1-Butyl-, 2-Butyl- oder 2-Methyl-2-propyl-Gruppen substituierte Derivate.
• • Dimethyl-cyclohexylamin, Methyl-dicyclohexylamin, Diethyl-cyclohexylamin, Ethyl-dicyclohexylamin, Dimethyl-cyclopentylamin, Methyl-dicyclopentylamin.
• • Triphenylamin, Methyl-diphenylamin, Ethyl-diphenylamin, Propyl-diphenylamin, Butyl-diphenylamin, 2-Ethyl-hexyl-diphenylamin, Dimethyl-phenylamin, Diethyl-phenylamin, Dipropyl-phenylamin, Dibutyl-phenylamin, Bis(2-Ethyl-hexyl)-phenylamin, Tribenzylamin, Methyl-dibenzylamin, Ethyl-dibenzylamin und deren durch eine oder mehrere Methyl-, Ethyl-, 1-Propyl, 2-Propyl-, 1-Butyl-, 2-Butyl- oder 2-Methyl-2-propyl-Gruppen substituierte Derivate.
• • N-C₁-bis-C₁₂-Alkyl-piperidine, N,N-Di-C₁-bis-C₁₂-Alkyl-piperazine, N-C₁-bis-C₁₂-Alkyl-pyrrolidone, N-C₁-bis-C₁₂-Alkyl-imidazole und deren durch eine oder mehrere Methyl-, Ethyl-, 1-Propy-, 2-Propyl-, 1-Butyl-, 2-Butyl- oder 2-Methyl-2-propyl-Gruppen substituierte Derivate.
• • 1,8-Diazabicyclo[5.4.0]undec-7-en („DBU“), 1,4-Diazabicyclo[2.2.2]octan („DAB- CO“), N-Methyl-8-azabicyclo[3.2.1]octan („Tropan“), N-Methyl-9-azabicyclo[3.3.1]nonan („Granatan“), 1-Azabicyclo[2.2.2]octan („Chinuclidin“).

Examples of suitable tertiary amines (A1) include:

• Trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n -decylamine, tri-n-undecylamine, tri-n-dodecylamine, tri-n-tridecylamine, tri-n-tetradecylamine, tri-n-pentadecylamine, tri-n-hexadecylamine, tri (2-ethylhexyl) amine.
• Dimethyl-decylamine, dimethyldodecylamine, dimethyl-tetradecylamine, ethyl-di- (2-propyl) amine, dioctyl-methylamine, dihexyl-methylamine.
• Tricyclopentylamine, tricyclohexylamine, tricycloheptylamine, tricyclooctylamine and their substituted by one or more methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl or 2-methyl-2-propyl groups derivatives.
• Dimethylcyclohexylamine, methyldicyclohexylamine, diethylcyclohexylamine, ethyldicyclohexylamine, dimethylcyclopentylamine, methyldicyclopentylamine.
• • triphenylamine, methyl-diphenylamine, ethyl-diphenylamine, propyl-diphenylamine, butyl-diphenylamine, 2-ethyl-hexyl-diphenylamine, dimethyl-phenylamine, diethyl-phenylamine, dipropyl-phenylamine, dibutyl-phenylamine, bis (2-ethyl-hexyl ) -phenylamine, tribenzylamine, methyl-dibenzylamine, ethyl-dibenzylamine and theirs by one or more methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl or 2-methyl-2-one propyl groups substituted derivatives.
• • NC ₁ -bis-C ₁₂ -alkyl-piperidines, N, N-di-C ₁ -bis-C ₁₂ -alkyl-piperazines, NC ₁ -bis-C ₁₂ -alkyl-pyrrolidone, NC ₁ -bis-C ₁₂ Alkyl imidazoles and their by one or more methyl, ethyl, 1-propy, 2-propyl, 1-butyl, 2-butyl or 2-methyl-2-propyl groups substituted derivatives.
• • 1,8-diazabicyclo [5.4.0] undec-7-ene ("DBU"), 1,4-diazabicyclo [2.2.2] octane ("DABCO"), N-methyl-8-azabicyclo [3.2 .1] octane ("tropane"), N-methyl-9-azabicyclo [3.3.1] nonane ("garnetane"), 1-azabicyclo [2.2.2] octane ("quinuclidine").

Particularly preferred in the process according to the invention as tertiary amine (A1) is an amine in which the radicals R ¹ , R ² , R ^{3 are} independently selected from the group C ₁ - to C ₁₂ alkyl, C ₅ - to C ₈ -cycloalkyl, benzyl and phenyl.

Particularly preferred in the process according to the invention as the tertiary amine (A1) is a saturated, d. H. only single bond-containing amine.

An especially suitable amine in the process according to the invention is a tertiary amine of the general formula (A1) in which the radicals R ¹ , R ² , R ^{3 are} independently selected from the group C ₅ - to C ₈ -alkyl, in particular tri -n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, dimethylcyclohexylamine, methyldicyclohexylamine, dioctylmethylamine and dimethyldecylamine.

The radicals R ¹ , R ² and R ^{3 of} the tertiary amine (A1) used are particularly preferably selected independently of one another from branched or unbranched pentyl, hexyl, heptyl and octyl groups.

Preferred are unbranched alkyl groups and the tertiary amine (A1) is selected from the group consisting of tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine and tri-n-octylamine. The tertiary amines (A1) may contain other amines as impurities due to the production.

In the process according to the invention, mixtures of two or more different tertiary amines (A1) can also be used.

In one embodiment of the process according to the invention, one (1) tertiary amine of the general formula (A1) is used.

Most preferably, in the process according to the invention, tri-n-hexylamine is used as the tertiary amine of the general formula (A1). The tri-n-hexylamine used may contain other amines as impurities due to the production process.

The tertiary amine (A1) in the process according to the invention is preferably liquid in all process stages.

In the process according to the invention, at least one polar solvent is selected in process step (a1) in the hydrogenation of carbon dioxide from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1. propanol and water used.

In the context of the present invention, "polar solvent" is understood to mean both one (1) polar solvent and mixtures of two or more polar solvents.

The polar solvent used in the process according to the invention is preferably selected or matched with the tertiary amine (A1) so that it preferably meets the following criteria with regard to the phase behavior in the hydrogenation reactor in process step (a1): The polar solvent should preferably be selected such that the hydrogenation mixture (H) obtained in process step (a1), optionally after addition of water, at least two-phase. The polar solvent should be enriched in the lower phase (U1), ie the lower phase (U1) should contain the major part of the polar solvent. In the context of the present invention, "enriched" or "main part" with respect to the polar solvent is a weight fraction of the polar solvent in the lower phase (U1) of> 50%, based on the total weight of the polar solvent in the liquid phases (upper phase (O1 ) and lower phase (U1)) in the hydrogenation reactor.

The weight fraction of the polar solvent in the lower phase (U1) is preferably> 70%, in particular> 90%, in each case based on the total weight of the polar solvent in the upper phase (O1) and the lower phase (U1).

Selection of the polar solvent satisfying the above criteria is generally accomplished by a simple experiment in which the phase behavior and solubility of the polar solvent in the liquid phases (upper phase (O1) and lower phase (U1)) under the process conditions in process stage (a1) can be determined experimentally.

The polar solvent may be a pure polar solvent or a mixture of two or more polar solvents as long as the polar solvent or mixture of polar solvents meets the above-described phase behavior and solubility criteria in the upper phase (O1) and Subphase (U1) in the hydrogenation reactor in process step (a1).

In one embodiment of the process according to the invention, a single-phase hydrogenation mixture is first obtained in step (a1) which is converted by the addition of water into the biphasic hydrogenation mixture (H).

In a further embodiment of the process according to the invention, the biphasic hydrogenation mixture (H) is obtained directly in step (a1). The biphasic hydrogenation mixture (H) obtained according to this embodiment can be directly fed to the work-up according to step (a2). It is also possible to additionally add water to the biphasic hydrogenation mixture (H) before further processing in step (a2). This can lead to an increase in the distribution coefficient P _{K of} the complex catalyst.

In the event that used as the polar solvent, a mixture of alcohol (selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and 2-methyl-1-propanol) and water is, the ratio of alcohol to water is chosen so that together with the formic acid-amine adduct (A2) and the tertiary amine (A1) an at least two-phase hydrogenation mixture (H) containing the upper phase (O1) and the lower phase (U1 ) trains.

It is also possible, in the event that the polar solvent is a mixture of alcohol (selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and 2-methyl 1-propanol) and water is used, the ratio of alcohol to water is chosen so that, together with the formic acid-amine adduct (A2) and the tertiary amine (A1) first a single-phase hydrogenation mixture is formed, which is subsequently by addition of Water is transferred to the biphasic hydrogenation mixture (H).

In a further particularly preferred embodiment, the polar solvent used is water, methanol or a mixture of water and methanol.

The use of diols and their formic acid esters, polyols and their formic acid esters, sulfones, sulfoxides and open-chain or cyclic amides as the polar solvent is not preferred.

The molar ratio of the polar solvent or solvent mixture used in the process according to the invention in process step (a1) to the tertiary amine (A1) used is generally 0.5 to 30 and preferably 1 to 20.

The complex catalyst used in the process according to the invention in process step (a1) for the hydrogenation of carbon dioxide comprises at least one element selected from groups 8, 9 and 10 of the Periodic Table (IUPAC nomenclature). Groups 8, 9 and 10 of the Periodic Table include Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt. In process step (a1), one (1) complex catalyst or a mixture of two or more complex catalysts can be used. Preferably, one (1) catalyst is used. In the context of the present invention, "complex catalyst" is understood to mean both one (1) complex catalyst and mixtures of two or more complex catalysts.

Preferably, the complex catalyst contains at least one element selected from the group consisting of Ru, Rh, Pd, Os, Ir and Pt, more preferably at least one element selected from the group consisting of Ru, Rh and Pd. Most preferably, the complex catalyst Ru contains.

As the complex catalyst, a complex-type compound of the above-mentioned elements is preferably used. The reaction in process step (a1) is preferably carried out homogeneously catalyzed.

In the context of the present invention, "homogeneously catalyzed" means that the catalytically active part of the complex catalyst is at least partially dissolved in the liquid reaction medium. In a preferred embodiment, at least 90% of the complex catalyst used in process step (a1) is dissolved in the liquid reaction medium, more preferably at least 95%, particularly preferably more than 99%, most preferably the complex catalyst is completely dissolved in the liquid reaction medium (100%). ), in each case based on the total amount of complex catalyst present in the liquid reaction medium.

The amount of the metal components of the complex catalyst in process step (a1) is generally from 0.1 to 5000 ppm by weight, preferably from 1 to 800 ppm by weight, and more preferably from 5 to 800 ppm by weight, based in each case on the entire liquid reaction mixture (Rg) in the hydrogenation reactor. The complex catalyst is selected so that it is enriched in the upper phase (O1), ie the upper phase (O1) contains the main part of the complex catalyst. In the context of the present invention, "enriched" or "main part" with respect to the complex catalyst is a distribution coefficient of the complex catalyst P _K = [concentration of the complex catalyst in the upper phase (O 1)] / [concentration of the complex catalyst in the lower phase (U 1)] of> 1 to understand. A distribution coefficient P _K > 1.5 is preferred and a distribution coefficient P _K > 4 is particularly preferred. The complex catalyst is generally selected by a simple experiment in which the phase behavior and the solubility of the complex catalyst in the liquid phases (upper phase (O 1) and subphase (U1)) under the process conditions in process step (a1).

Because of their good solubility in tertiary amines used in the process according to the invention as complex catalysts preferably homogeneous complex catalysts, in particular an organometallic complex compound containing an element from the 8th, 9th or 10th group of the periodic table and at least one phosphine group with at least one unbranched or branched, acyclic or cyclic, aliphatic radical having 1 to 20 carbon atoms, wherein individual carbon atoms may also be substituted by> P-. For the purposes of branched cyclic aliphatic radicals, radicals such as, for example, -CH ₂ -C ₆ H _{11 are also} included. Examples of suitable radicals are methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 1- (2-methyl) propyl, 2- (2-methyl) propyl, 1-pentyl, 1-hexyl, 1 Heptyl, 1-octyl, 1-nonyl, 1-decyl, 1-undecyl, 1-dodecyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl, methylcyclopentyl, methylcyclohexyl, 1- (2-methyl) -pentyl, 1- (2-ethyl ) -hexyl, 1- (2-propyl) heptyl and norbornyl. The unbranched or branched, acyclic or cyclic, aliphatic radical preferably contains at least 1 and preferably not more than 10 carbon atoms. In the case of an exclusively cyclic radical in the above-mentioned sense, the number of carbon atoms is 3 to 12 and preferably at least 4 and preferably at most 8 carbon atoms. Preferred radicals are ethyl, 1-butyl, sec-butyl, 1-octyl and cyclohexyl.

The phosphine group can contain one, two or three of the above-mentioned unbranched or branched, acyclic or cyclic, aliphatic radicals. These can be the same or different. Preferably, the phosphine group contains three of the above-mentioned unbranched or branched, acyclic or cyclic, aliphatic radicals, with particular preference, all three radicals are the same. Preferred phosphines are P (nC _n H _{2n + 1} ) ₃ with n being 1 to 20, more preferably tri-n-butylphosphine, tri-n-octylphosphine and 1,2-bis (dicyclohexylphosphino) ethane.

As already mentioned above, in the stated unbranched or branched, acyclic or cyclic, aliphatic radicals, individual carbon atoms may also be substituted by> P-. Thus, multidentate, for example, bidentate or tridentate phosphine ligands are also included. These preferably contain the

If the phosphine group contains radicals other than the abovementioned unbranched or branched, acyclic or cyclic, aliphatic radicals, these generally correspond to those which are customarily used in the case of phosphine ligands for organometallic complex catalysts. As examples of its called phenyl, tolyl and xylyl.

The organometallic complex compound may contain one or more, for example two, three or four, of the abovementioned phosphine groups having at least one unbranched or branched, acyclic or cyclic, aliphatic radical. The remaining ligands of the organometallic complex may be of different nature. Examples which may be mentioned are hydride, fluoride, chloride, bromide, iodide, formate, acetate, propionate, carboxylate, acetylacetonate, carbonyl, DMSO, hydroxide, trialkylamine, alkoxide.

The homogeneous catalysts can be prepared both directly in their active form and starting from customary standard complexes such as [M (p-cymene) Cl ₂ ] ₂ , [M (benzene) Cl ₂ ] _n , [M (COD) (allyl)], [MCl ₃ x H ₂ O], [M (acetylacetonate) ₃ ], [M (COD) Cl ₂ ] ₂ , [M (DMSO) ₄ Cl ₂ ] with M being the same as element from the 8th, 9th or 10th Group of the periodic table with the addition of the corresponding or the corresponding phosphine ligands are produced only under reaction conditions.

Homogeneous complex catalysts which are preferred in the process according to the invention are selected from the group consisting of [Ru (P ⁿ Bu ₃ ) ₄ (H) ₂ ], [Ru (P ⁿ octyl ₃ ) ₄ (H) ₂ ], [Ru (P ⁿ Bu ₃ ) ₂ (1,2-bis (dicyclohexylphosphino) ethane) (H) _2], [Ru (P ^n-octyl _{3) 2} (1,2-bis (dicyclohexylphosphino) ethane) (H) _2], [Ru (PEt ₃ ) ₄ (H) ₂ ] [Ru (P ⁿ octyl ₃ ) 1,2-bis (dicyclohexylphosphino) ethane) (CO) (H) ₂ ], [Ru (P ⁿ octyl ₃ ) 1,2-bis ( dicyclohexylphosphino) ethane) (CO) (H) (HCOO)], [Ru (P ⁿ butyl ₃ ) 1,2-bis (dicyclohexylphosphino) ethane) (CO) (H) ₂ ], [Ru (P ⁿ butyl ₃ ) 1,2-bis (dicyclohexylphosphino) ethane) (CO) (H) (HCOO)], [Ru (P ⁿ ethyl ₃ ) 1,2-bis (dicyclohexylphosphino) ethane] (CO) (H) ₂ ], [Ru (P ⁿ ethyl ₃ ) 1,2-bis (dicyclohexylphosphino) ethane] (CO) (H) (HCOO)], [Ru (P ⁿ octyl ₃ ) 1,1-bis (dicyclohexylphosphino) methane ) (CO) (H) _2], [Ru (P ^n-octyl ₃₎ 1,1-bis (dicyclohexylphosphino) methane) (CO) (H) (HCOO)], [Ru (P ⁿ butyl ₃₎ 1, 1-bis (dicyclohexylphosphino) -methane) (CO) (H) ₂ ], [Ru (P ⁿ butyl ₃ ) 1,1-bis (dicyclohexylphosphino) metha n) (CO) (H) (HCOO)], [Ru (P ⁿ ethyl ₃ ) 1,1-bis (dicyclohexylphosphino) -methane) (CO) (H) ₂ ], [Ru (P ⁿ ethyl ₃ ) 1 , 1-bis (dicyclohexylphosphino) -methane) (CO) (H) (HCOO)], [Ru (P ⁿ octyl ₃ ) 1,2-bis (diphenylphosphino) ethane] (CO) (H) ₂ ], [ Ru (P ⁿ octyl ₃ ) 1,2-bis (diphenylphosphino) ethane) (CO) (H) (HCOO)], [Ru (P ⁿ butyl ₃ ) 1,2-bis (diphenylphosphino) ethane] (CO ) (H) ₂ ], [Ru (P ⁿ butyl ₃ ) 1,2-bis (diphenylphosphino) ethane) (CO) (H) (HCOO)], [Ru (P ⁿ ethyl ₃ ) 1,2-bis (diphenlyphosphino) ethane) (CO) (H) ₂ ], [Ru (P ⁿ ethyl ₃ ) 1,2-bis (diphenylphosphino) ethane] (CO) (H) (HCOO)], [Ru (P ⁿ octyl ₃₎ 1,1-bis (diphenylphosphino) methane) (CO) (H) _2], [Ru (P ^n-octyl ₃₎ 1,1-bis (diphenylphosphino) methane) (CO) (H) (HCOO )], [Ru (P ⁿ butyl ₃ ) 1,1-bis (diphenylphosphino) -methane) (CO) (H) ₂ ], [Ru (P ⁿ butyl ₃ ) 1,1-bis (diphenylphosphino) -methane] (CO) (H) (HCOO)], [Ru (P ⁿ ethyl ₃ ) 1,1-bis (diphenylphosphino) -methane) (CO) (H) ₂ ], [Ru (P ⁿ ethyl ₃ ) 1,1 -bis (diphenylphosphino) methane) (CO) (H) (HCOO)].

With these, TOF (turn-over-frequency) values of greater than 1000 h ^-1 can be achieved in the hydrogenation of carbon dioxide.

The hydrogenation of carbon dioxide in process step (a1) is preferably carried out in the liquid phase at a temperature in the range of 20 to 200 ° C and a total pressure in the range of 0.2 to 30 MPa abs. Preferably, the temperature is at least 30 ° C and more preferably at least 40 ° C and preferably at most 150 ° C, more preferably at most 120 ° C and most preferably at most 80 ° C. The total pressure is preferably at least 1 MPa abs and more preferably at least 5 MPa abs and preferably at most 20 MPa abs.

In a preferred embodiment, the hydrogenation is carried out in process step (a1) at a temperature in the range of 40 to 80 ° C and a pressure in the range of 5 to 15 MPa abs.

The partial pressure of the carbon dioxide in process step (a1) is generally at least 0.5 MPa and preferably at least 2 MPa and generally at most 8 MPa. In a preferred embodiment, the hydrogenation in process step (a1) takes place at a partial pressure of the carbon dioxide in the range from 2 to 7.3 MPa.

The partial pressure of the hydrogen in process step (a1) is generally at least 0.5 MPa and preferably at least 1 MPa and generally at most 25 MPa and preferably at most 10 MPa. In a preferred embodiment, the hydrogenation in process step (a1) takes place at a partial pressure of the hydrogen in the range from 1 to 15 MPa.

The molar ratio of hydrogen to carbon dioxide in the reaction mixture (Rg) in the hydrogenation reactor is preferably 0.1 to 10 and particularly preferably 1 to 3.

The molar ratio of carbon dioxide to tertiary amine (A1) in the reaction mixture (Rg) in the hydrogenation reactor is preferably 0.1 to 10 and more preferably 0.5 to 3.

In principle, all reactors which are suitable for gas / liquid reactions under the given temperature and the given pressure can be used as hydrogenation reactors. Suitable standard reactors for gas / liquid reaction systems are, for example, in KD Henkel, "Reactor Types and their Industrial Applications," in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH Verlag GmbH & Co. KGaA, DOI: 10.1002 / 14356007.b04_087, Chapter 3.3 "Reactors for gas-liquid reactions" specified. Examples which may be mentioned stirred tank reactors, tubular reactors or bubble column reactors.

The hydrogenation of carbon dioxide can be carried out batchwise or continuously in the process according to the invention. In the batchwise procedure, the reactor is equipped with the desired liquid and optionally solid feedstocks and auxiliaries, and then carbon dioxide and the polar solvent are pressed to the desired pressure at the desired temperature. After the end of the reaction, the reactor is normally depressurized and the two liquid phases formed are separated from one another. In the continuous mode of operation, the feedstocks and auxiliaries, including carbon dioxide and hydrogen, are added continuously. Accordingly, the liquid phases are continuously discharged from the reactor, so that the liquid level in the reactor remains the same on average. Preference is given to the continuous hydrogenation of carbon dioxide.

The average residence time of the components in the hydrogenation reactor contained in the reaction mixture (Rg) is generally from 5 minutes to 5 hours.

In the homogeneous-catalyzed hydrogenation, a hydrogenation mixture (H) is obtained in process step (a1) which contains the complex catalyst, the polar solvent, the tertiary amine (A1) and the formic acid-amine adduct (A2).

In the context of the present invention, "formic acid-amine adduct (A2)" is understood as meaning both one (1) formic acid-amine adduct (A2) and mixtures of two or more formic acid-amine adducts (A2). Mixtures of two or more formic acid-amine adducts (A2) are obtained in process step (a1) if two or more tertiary amines (A1) are used in the reaction mixture used (Rg).

In a preferred embodiment of the process according to the invention, a reaction mixture (Rg) is used in process stage (a1) which contains a (1) tertiary amine (A1), a hydrogenation mixture (H) being obtained which comprises one (1) formic acid amine. Adduct (A2) contains.

In a particularly preferred embodiment of the process according to the invention, a reaction mixture (Rg) is used in process step (a1) which comprises tri-n-hexylamine as the tertiary amine (A1) to give a hydrogenation mixture (H) which comprises the formic acid amine. Adduct of tri-n-hexylamine and formic acid and corresponds to the following formula (A3) N (n-hexyl) ₃ * x _i HCOOH (A3).

In the formic acid-amine adduct of the general formula (A2), the radicals R ¹ , R ² , R ^{3 have} the abovementioned meanings, the preferences mentioned there correspondingly apply.

In the general formulas (A2) and (A3), x _{i is} in the range of 0.4 to 5. The factor x _i indicates the average composition of the formic acid-amine adduct (A 2) or (A 3), ie the ratio of bound tertiary amine (A1) to bound formic acid in the formic acid-amine adduct (A2) or (A3).

The factor x _i can be determined, for example, by determining the formic acid content by acid-base titration with an alcoholic KOH solution against phenolphthalein. In addition, one is Determination of the factor x _i by determination of the amine content by gas chromatography possible. The exact composition of the formic acid-amine adduct (A2) or (A3) depends on many parameters, such as the concentrations of formic acid and tertiary amine (A1), the pressure, the temperature and the presence and nature of other components, in particular of the polar solvent.

Therefore, the composition of the formic acid-amine adduct (A2) or (A3), ie the factor x _i , can also change over the individual process stages. For example, after removal of the polar solvent, a formic acid-amine adduct (A2) or (A3) with a higher formic acid content generally forms, the excess bound tertiary amine (A1) being formed from the formic acid-amine adduct (A2 ) is split off and forms a second phase.

In process step (a1), a formic acid-amine adduct (A2) or (A3) is generally obtained in which x _{i is} in the range from 0.4 to 5, preferably in the range from 0.7 to 1.6 ,

The formic acid-amine adduct (A2) is enriched in the lower phase (U1), i. the lower phase (U1) contains the major part of the formic acid-amine adduct. In the context of the present invention, "enriched" or "main part" with respect to the formic acid-amine adduct (A2) is a weight fraction of the formic acid-amine adduct (A2) in the lower phase (U1) of> 50% to understand the total weight of the formic acid-amine adduct (A2) in the liquid phases (upper phase (O1) and lower phase (U1)) in the hydrogenation reactor.

The weight fraction of the formic acid-amine adduct (A2) in the lower phase (U1) is preferably> 70%, in particular> 90%, in each case based on the total weight of the formic acid-amine adduct (A2) in the upper phase (O1). and the lower phase (U1).

Workup of the hydrogenation mixture (H); Process step (a2)

In this case, the hydrogenation mixture (H) obtained in process stage (a1) is further worked up in a first phase separation apparatus by phase separation to obtain a lower phase (U1) containing the formic acid-amine adduct (A2), the polar solvent and residues of the complex catalyst and an upper phase (O1) containing the complex catalyst and the tertiary amine (A1).

In a preferred embodiment, the upper phase (O1) is recycled to the hydrogenation reactor. The lower phase (U1) is forwarded to the extraction unit.

The separation of the hydrogenation mixture (H) obtained in process step (a1) is generally carried out by gravimetric phase separation. Suitable phase separation devices are, for example, standard apparatuses and standard methods, which are described, for example, in US Pat E. Muller et al., "Liquid-Liquid Extraction", in Ullman's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH Verlag GmbH & Co. KGaA, DOI: 10.1002 / 14356007.b93_06, Chapter 3 "Apparatus" can be found. In general, the liquid phase enriched with the formic acid-amine adducts (A2) and the polar solvent is heavier and forms the lower phase (U1).

The phase separation may take place, for example, after relaxation to about or near atmospheric pressure and cooling of the liquid hydrogenation mixture, for example at about or near ambient temperature.

In the present invention, it has been found that in the present system, that is, one with the formic acid-amine adducts (A2) and the polar solvent enriched lower phase (U1) and one with the tertiary amine (A1) and the complex catalyst Enriched upper phase (O1), both liquid phases with a suitable combination of the polar solvent and the tertiary amine (A1) very well separated even at elevated pressure or elevated temperature. It is also possible to carry out the phase separation directly in the hydrogenation reactor. In this embodiment, the hydrogenation reactor simultaneously acts as the first phase separation device. In this case, the upper phase (O1) remains in the hydrogenation reactor and the lower phase (U1) is fed to the extraction unit.

In one embodiment, the process according to the invention is carried out in such a way that the pressure and the temperature in the hydrogenation reactor and in the first phase separator are the same or approximately the same, whereby a pressure difference of up to +/- 0.5 MPa or approximately equal to a temperature difference of up to +/- 10 ° C is understood.

The lower phase (U1) obtained after phase separation is subsequently subjected in an extraction unit to extraction with a tertiary amine (A1) as extractant to remove the residues of the complex catalyst to obtain a raffinate (R2) containing the formic acid-amine adduct (A2) and the polar solvent and an extract (E2) containing the tertiary amine (A1) and the residues of the complex catalyst.

In a preferred embodiment, the same tertiary amine (A1) used in process step (a1) in the reaction mixture (Rg) is used as extractant, so that the statements and preferences made with regard to the tertiary amine (a1) for process step (a1) A1) apply correspondingly to process step (a2).

The extract (E2) obtained in process step (a2) is recycled in a preferred embodiment to the hydrogenation reactor in process step (a1). This allows efficient recovery of the expensive complex catalyst.

The tertiary amine (A1) which is obtained in the reaction of the formic acid-amine adduct (A2) according to step (b) or (bc) is preferably used as the extraction agent in process step (a2).

The extraction is carried out in process step (a2) generally at temperatures in the range of 30 to 100 ° C and pressures in the range of 0.1 to 8 MPa. The extraction can also be carried out under hydrogen pressure.

The extraction of the complex catalyst can be carried out in any suitable apparatus known to those skilled in the art, preferably in countercurrent extraction columns, mixer-settler cascades or combinations of mixer-settler cascades and countercurrent extraction columns.

If appropriate, fractions of individual components of the polar solvent from the subphase (U1) to be extracted in the extraction agent, the tertiary amine (A1), are dissolved in addition to the complex catalyst. This is not a disadvantage for the process, since the already extracted amount of polar solvent does not have to be supplied to the solvent removal and thus may save evaporation energy.

Reaction of the formic acid-amine adduct (A2); Process Stage (b) In Process Stage (b), the formic acid-amine adduct (A2) prepared in step (a) is selected from at least one metal hydroxide selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and aluminum hydroxide to form at least one metal formate the group consisting of sodium formate, potassium formate, magnesium formate, calcium formate and aluminum formate reacted.

In the context of the present invention, "metal hydroxide" is understood as meaning both one (1) metal hydroxide and mixtures of two or more metal hydroxides.

In the context of the present invention, "metal formate" is understood as meaning both one (1) metal formate and mixtures of two or more metal formates.

The metal hydroxides may contain impurities due to their production. However, the amount of impurities is preferably below 20 wt .-%, preferably below 15 wt .-%, each based on the total amount of the metal hydroxide used.

Preferred metal hydroxides are selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide and aluminum hydroxide.

Particularly preferred metal hydroxides are sodium hydroxide or potassium hydroxide. As potassium hydroxide technical potassium hydroxide can be used with a potassium hydroxide content of at least 85 wt .-%, which contains as impurity potassium carbonate.

Mixtures of two or more metal formates are obtained in process step (b) when the formic acid-amine adduct (A2) is reacted with two or more metal hydroxides. Preferably, the formic acid-amine adduct (A2) is reacted with only one metal hydroxide, whereby only one metal formate is obtained.

In the reaction of the formic acid-amine adduct (A2) with a metal hydroxide, the corresponding metal formate, water and the corresponding tertiary amine (A1) are formed.

In a preferred embodiment, sodium formate is prepared in process step (b). The reaction in step (b) then follows the reaction equation (1) NR ¹ R ² R ³ * x _i HCOOH + NaOH → (HCOO) Na + H ₂ O + NR ¹ R ² R ³ (1); not stoichiometric representation.

In a further preferred embodiment, potassium formate is prepared in process step (b). The reaction in step (b) then follows the reaction equation (2) NR ¹ R ² R ³ * x _i → HCOOH + KOH (HCOO) K + H ₂ O + NR ¹ R ² R ³ (2); not stoichiometric representation.

In a further preferred embodiment, calcium formate is produced in process step (b). The reaction in step (b) then follows the reaction equation (3) NR ¹ R ² R ³ * x _i HCOOH + Ca (OH) ₂ → (HCOO) ₂ Ca + H ₂ O + NR ¹ R ² R ³ (3); not stoichiometric representation.

In a further preferred embodiment, magnesium formate is prepared in process step (b). The reaction in step (b) then follows the reaction equation (4) NR ¹ R ² R ³ * x _i HCOOH + Mg (OH) ₂ → (HCOO) ₂ Mg + H ₂ O + NR ¹ R ² R ³ (4); not stoichiometric representation.

In a further preferred embodiment, aluminum formate is produced in process step (b). The reaction in step (b) then follows the reaction equation (5) NR ¹ R ² R ³ * x _i HCOOH + Al (OH) ₃ → (HCOO) ₃ Al + H ₂ O + NR ¹ R ² R ³ (5); not stoichiometric representation.

The raffinate (R2) obtained in step (a) according to a preferred embodiment contains the formic acid-amine adduct (A2) and the polar solvent. In a preferred embodiment, the raffinate (R2) is further worked up before the reaction in step (b).

• (ba) Abtrennung des mindestens einen polaren Lösungsmittels aus dem Raffinat (R2) in einer ersten Destillationsvorrichtung unter Erhalt eines Destillats (D1) enthaltend das mindestens eine polare Lösungsmittel, das in den Hydrierreaktor in Schritt (a1) rückgeführt wird, und eines zweiphasigen Sumpfgemischs (S1) enthaltend eine Oberphase (O2), die das tertiäre Amin (A1) enthält, und eine Unterphase (U2), die das Ameisensäure-Amin-Addukt (A2) enthält,
• (bb) gegebenenfalls Aufarbeitung des in Schritt (ba) erhaltenen Sumpfgemischs (S1) durch Phasentrennung in einer zweiten Phasentrennvorrichtung in die Oberphase (O2) und die Unterphase (U2),
• (bc) Umsetzen des im Sumpfgemisch (S1) beziehungsweise gegebenenfalls in der Unterphase (U2) enthaltenen Ameisensäure-Amin-Addukts (A2) in Gegenwart von Wasser mit einem Metallhydroxid ausgewählt aus der Gruppe bestehend aus Natriumhydroxid, Kaliumhydroxid, Magnesiumhydroxid, Calciumhydroxid und Aluminiumhydroxid in einem Metallformiat-Reaktor unter Erhalt eines mindestens zweiphasigen Gemischs (MF) enthaltend eine Oberphase (O3), die das entsprechende tertiäre Amin (A1) enthält, und eine Unterphase (U3), die das Metallformiat und Wasser enthält.

In a preferred embodiment, step (b) comprises the following steps

• (ba) separating the at least one polar solvent from the raffinate (R2) in a first distillation apparatus to obtain a distillate (D1) containing the at least one polar solvent which is recycled to the hydrogenation reactor in step (a1) and a biphasic mixture of bottoms ( S1) containing an upper phase (O2) containing the tertiary amine (A1) and a lower phase (U2) containing the formic acid-amine adduct (A2),
• (bb) if appropriate working up of the bottom mixture (S1) obtained in step (ba) by phase separation in a second phase separation device into the upper phase (O2) and the lower phase (U2),
• (bc) reacting the formic acid-amine adduct (A2) present in the bottom mixture (S1) or optionally in the bottom phase (U2) in the presence of water with a metal hydroxide selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and aluminum hydroxide a metal formate reactor to obtain an at least biphasic mixture (MF) containing an upper phase (O3) containing the corresponding tertiary amine (A1) and a lower phase (U3) containing the metal formate and water.

In process stage (ba), the polar solvent is separated off from the raffinate (R2) in a first distillation apparatus. In the first distillation apparatus, a distillate (D1) and a two-phase bottoms mixture (S1) are obtained. The distillate (D1) contains the separated polar solvent and in a preferred embodiment is recycled to the hydrogenation reactor in step (a1).

The bottoms mixture (S1) contains the upper phase (O2) containing the tertiary amine (A1) and a lower phase (U2) containing the formic acid-amine adduct (A2). In one embodiment of the process according to the invention, in the first distillation apparatus in process stage (ba), the polar solvent is partially separated, so that the bottom mixture (S1) contains not yet separated polar solvent. In process stage (ba), for example, 5 to 98% by weight of the polar solvent contained in the raffinate (R2), preferably 50 to 98% by weight and more preferably 80 to 98% by weight, can be separated, in each case based on the total weight of the polar solvent contained in the raffinate (R2).

In a further embodiment of the process according to the invention, the polar solvent is completely separated off in the first distillation apparatus in process stage (ba). In the context of the present invention, "completely separated off" is a separation of more than 98% by weight of the polar solvent contained in the raffinate (R 2), preferably more than 98.5% by weight, particularly preferably more than 99% by weight. %, in particular more than 99.5% by weight, understood, in each case based on the total weight of the polar solvent contained in the raffinate (R2).

The separation of the polar solvent from the raffinate (R2) can be carried out, for example, in an evaporator or in a distillation unit consisting of evaporator and column, the column being filled with packings, fillers and / or trays.

The separation of the polar solvent is preferably carried out at a bottom temperature at which no free formic acid is formed from the formic acid-amine adduct (A2) at a given pressure. The factor x _{i of} the formic acid-amine adduct (A2) in the first distillation apparatus is generally in the range of 0.4 to 3, preferably in the range of 0.6 to 1.8, particularly preferably in the range of 0.7 to 1.7.

In general, the bottom temperature in the first distillation apparatus is at least 20 ° C, preferably at least 50 ° C and particularly preferably at least 70 ° C, and generally at most 210 ° C, preferably at most 190 ° C. The temperature in the first distillation apparatus is generally in the range of 20 ° C to 210 ° C, preferably in the range of 50 ° C to 190 ° C. The pressure in the first distillation apparatus is generally at least 0.001 MPa abs, preferably at least 0.005 MPa abs and more preferably at least 0.01 MPa abs and generally at most 1 MPa abs and preferably at most 0.1 MPa abs. The pressure in the first distillation apparatus is generally in the range of 0.0001 MPa abs to 1 MPa abs, preferably in the range of 0.005 MPa abs to 0.1 MPa abs and more preferably in the range of 0.01 MPa abs to 0.1 MPa abs.

In the removal of the polar solvent in the first distillation apparatus, the formic acid-amine adduct (A2) and free tertiary amine (A1) can be obtained in the bottom of the first distillation apparatus, since the removal of the polar solvent gives formic acid-amine adducts with a lower amine content , This forms a bottom mixture (S1) which contains the formic acid-amine adduct (A2) and the free tertiary amine (A1). The bottom mixture (S1) contains, depending on the separated amount of the polar solvent, the formic acid-amine adduct (A2) and optionally the free tertiary amine (A1) formed in the bottom of the first distillation apparatus. If appropriate, the bottoms mixture (S1) is further worked up in process stage (bb) for further workup and then fed to process stage (bc). It is also possible to feed the bottoms mixture (S1) from process step (ba) directly to process step (bc).

Since in the reaction of the formic acid-amine adduct (A2) to form a metal formate in any case, the tertiary amine (A1), a further work-up according to process step (bb) is not mandatory.

In process step (bb), the bottoms mixture (S1) obtained in step (ba) can be separated in a second phase separation device into the upper phase (O2) and the lower phase (U2). The lower phase (U2) is then further worked up according to process step (bc). In a preferred embodiment, the upper phase (O2) is recycled from the second phase separation device to the hydrogenation reactor in step (a1). In a further preferred embodiment, the upper phase (O2) is recycled from the second phase separation device to the extraction unit in step (a2). For process step (bb) and the second Phase separation device apply the comments and preferences for the first phase separation device in step (a2) accordingly.

The bottom mixture (S1) obtained according to step (ba) or the lower phase (U2) optionally obtained after the work-up according to step (bb) is reacted in a preferred embodiment according to step (bc).

The reaction of the formic acid-amine adduct (A2) according to step (b) or (bc) is preferably carried out at temperatures of 20 to 200 ° C, preferably 20 to 180 ° C, particularly preferably 30 to 100 ° C. The pressure is 0.01 to 10 MPa, preferably 0.05 to 7 MPa, more preferably 0.10 to 2 MPa. In particular, the reaction is carried out at atmospheric pressure (1013 mbara).

In the reaction of the formic acid-amine adduct (A2) with sodium hydroxide or potassium hydroxide to sodium formate or potassium formate, the molar ratio of formic acid contained in the formic acid-amine adduct (A2) to sodium hydroxide or potassium hydroxide in general in the range of 0.1 to 5, preferably in the range of 0.5 to 3, particularly preferably in 1.

In the reaction of the formic acid-amine adduct (A2) with magnesium hydroxide or calcium hydroxide to magnesium formate or calcium formate, the molar ratio of formic acid contained in the formic acid-amine adduct (A2) to magnesium hydroxide or calcium hydroxide in general in the range of 0.1 to 5, preferably in the range of 0.25 to 1.5, particularly preferably 0.5.

In the reaction of the formic acid-amine adduct (A2) with aluminum hydroxide to aluminum formate, the molar ratio of formic acid contained in the formic acid-amine adduct (A2) to aluminum hydroxide is generally in the range of 0.1 to 5, preferably in the range of 0.20 to 1, particularly preferably 0.33.

The reaction of the formic acid-amine adduct (A2) prepared according to step (a) with the metal hydroxide is preferably carried out in the presence of a polar solvent. Particularly preferred are methanol, water or mixtures of methanol and water. Most preferred is water.

The metal hydroxides may be added to the process step (b) solid or dissolved in a polar solvent, in particular dissolved in water.

The addition in dissolved form is preferred. Particularly preferably, the metal hydroxides are added as an aqueous solution containing 5 to 50 wt .-%, preferably 10 to 40 wt .-% and in particular 20 to 30 wt .-% metal hydroxide, each based on the total weight of the aqueous solution.

In the reaction of the formic acid-amine adduct (A2) provided in step (a) with the metal hydroxide in the presence of water, an at least biphasic mixture (MF) comprising a lower phase (U3) and an upper phase (O3) is formed. The lower phase (U3) contains the metal formate and water. The upper phase (O3) contains the corresponding tertiary amine (A1), which is formed during the reaction.

In the event that a superstoichiometric amount of metal hydroxide is used, the lower phase (U3) in addition to the metal formate and water additionally contains the excess metal hydroxide.

In the event that a substoichiometric amount of metal hydroxide is used, the conversion of the formic acid-amine adduct (A2) in the metal formate reactor is not complete. In this case, a three-phase mixture (MF) can be formed comprising a lower phase (U3), a middle phase (M3) and an upper phase (O3). The lower phase (U3) contains the metal formate and water, the middle phase (M3) contains unreacted formic acid-amine adduct (A2) and the upper phase (O3) contains the tertiary amine (A1).

In the case where a stoichiometric amount of metal hydroxide is used, the metal formate reactor generally forms a biphasic mixture (MF) containing a lower phase (U3) and an upper phase (O3). The lower phase (U3) contains the metal formate and water. The upper phase (O3) contains the tertiary amine (A1).

The free tertiary amine (A1) formed in the reaction is enriched in the upper phase (O3). The proportion by weight of the free tertiary amine (A1) in the upper phase (O3) is preferably> 70%, in particular> 90%, in each case based on the total weight of the tertiary free amine (A1) in the upper phase (O3), the lower phase (U3) and optionally in the middle phase (M3).

The metal formate formed during the reaction is enriched in the lower phase (U3). The weight fraction of the metal formate in the lower phase (U3) is preferably> 70%, in particular> 90%, in each case based on the total weight of the metal formate in the lower phase (U3), the upper phase (O3) and optionally the middle phase (M3). ,

The polar solvent, in particular water, is enriched in the lower phase (U3). The weight fraction of the polar solvent in the lower phase (U3) is preferably> 70%, in particular> 90%, in each case based on the total weight of the polar solvent in the lower phase (U3), the upper phase (O3) and optionally the middle phase ( M3).

The reaction according to the invention in process stage (b) or (bc) has the advantage that an at least two-phase mixture (MF) is formed. In a preferred embodiment, the at least two-phase mixture (MF) is separated in a third phase separation device into the lower phase (U3), the upper phase (O3) and optionally the middle phase (M3). This allows for easy separation of the lower phase (U3) containing the metal formate. The separation of the two phases (U3) and (O3) is generally carried out by gravimetric phase separation. Suitable for this purpose are, for example, standard equipment and standard methods, which are, for example, in E. Müller et. Al., Liquid Liquid Extraction, in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH Verlag GmbH & Co. KGaA, DOI: 10.1002 / 14356007.b03_06, Chapter 3 "Apparatus" can be found. For the third phase separation device, the statements and preferences for the first and second phase separation device apply accordingly.

The lower phase (U3) can be sold directly as an aqueous metal formate solution, in particular when using water. It is also possible to further process the lower phase (U3). Preferably, the water is separated from the lower phase (U3), whereby the metal formate is obtained as a solid.

The separation of the water can be carried out by methods known to those skilled in the art, for example in an evaporator or in a crystallizer.

The upper phase (O3) containing the tertiary amine (A1) can be reused. In a preferred embodiment, the upper phase (O3) is recycled in step (a) and used there to provide the formic acid-amine adduct.

The tertiary amine (A1) contained in the upper phase (O3) can be reacted, for example, with formic acid directly to the formic acid-amine adduct (A2).

The preparation of the formic acid-amine adduct (A2) can also be effected by hydrolysis of methyl formate to formic acid in the presence of the tertiary amine (A1) contained in the upper phase (O3).

The tertiary amine (A1) contained in the upper phase (O3) can also be used in a catalytic hydration of carbon monoxide, whereby the formic acid-amine adduct (A2) is obtained.

Preferably, the tertiary amine (A1) contained in the upper phase (O3) is used in a hydrogenation of carbon dioxide to formic acid, whereby the formic acid-amine adduct is obtained. The recycling of the upper phase to a process for the catalytic hydrogenation of carbon dioxide has the particular advantage that carbon dioxide is available in large quantities and is flexible in its source.

In a particularly preferred embodiment, the tertiary amine (A1) contained in the upper phase (O3) is recycled to the hydrogenation reactor in step (a1). With particular preference, the upper phase (O3) is recycled to the extraction unit in step (a2) and used there as extractant.

The reaction according to step (b) or (bc) can be carried out batchwise, but preferably continuously.

As a metal formate reactor standard reactors can be used, as for example in KD Henkel, "Reactor Types and their Industrial Applications" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH Verlag, Chapter 3.3 are indicated. Examples of metal formate reactors are stirred tank reactors, tubular reactors or bubble column reactors.

The separation of the two liquid phases (U3) and (O3) takes place in the third phase separation device. In a preferred embodiment, the metal formate reactor comprises a third phase separation device in which the at least two-phase mixture (MF) is separated. The phase separation can also be carried out in the metal formate reactor. The metal formate reactor then functions simultaneously as a reactor and third phase separation device.

The present invention is explained in more detail by the following figures and exemplary embodiments without being limited thereto.

The figures show in detail:

1 1 is a block diagram of a preferred embodiment of the process according to the invention for preparing the formic acid-amine adduct (A2) according to step (a),

2 2 shows a block diagram of a preferred embodiment of the process according to the invention for reacting the formic acid-amine adduct (A2) according to step (b) to form a metal formate,

3 a block diagram of another preferred embodiment of the method according to the invention for the reaction of the formic acid-amine adduct (A2) according to step (b) to form a metal formate.

In the 1 to 3 the reference signs have the following meanings:

LIST OF REFERENCE NUMBERS

I-1

Hydrierreaktor

II-1

erste Phasentrennvorrichtung

III-1

Extraktionseinheit

1

Strom enthaltend Kohlendioxid

2

Strom enthaltend Wasserstoff

3

Strom enthaltend Ameisensäure-Amin-Addukt (A2), Komplexkatalysator, polares Lösungsmittel, tertiäres Amin (A1); Hydriergemisch (H)

4

Strom enthaltend tertiäres Amin (A1), Komplexkatalysator; Oberphase (O1)

5

Strom enthaltend Ameisensäure-Amin-Addukt (A2), polares Lösungsmittel, Reste des Komplexkatalysators; Unterphase (U1)

6

Strom enthaltend tertiäres Amin (A1), Reste des Komplexkatalysators; Extrakt (E2)

7

Strom enthaltend Ameisensäure-Amin-Addukt (A2), polares Lösungsmittel; Raffinat (R2)

8

Strom enthaltend Extraktionsmittel (tertiäres Amin (A1))

9

Strom enthaltend polares Lösungsmittel

Fig. 2

IV-2

erste Destillationsvorrichtung

V-2

zweite Phasentrennvorrichtung (optional)

VI-2

Metallformiat-Reaktor

VII-2

dritte Phasentrennvorrichtung

7

Strom enthaltend Raffinat (R2)

8

Strom enthaltend tertiäres Amin (A1); (Oberphase O3)

9

Strom enthaltend polares Lösungsmittel; Destillat (D1)

10

Strom enthaltend tertiäres Amin (A1) (Oberphase O2) und Ameisensäure- Amin-Addukt (A2) (Unterphase U2); Sumpfgemisch (S1)

10a

Strom enthaltend Unterphase (U2)

10b

Strom enthaltend Oberphase (O2)

11

Strom enthaltend tertiäres Amin (A1) (Oberphase O3) und Metallformiat, Wasser (Unterphase U3); Gemisch (MF)

12

Strom enthaltend Metallformiat, Wasser (Unterphase U3)

13

Strom enthaltend Metallhydroxid gelöst in Wasser

In Fig. 3 haben die Bezugszeichen die folgenden Bedeutungen:

IV-3

erste Destillationsvorrichtung

V-3

zweite Phasentrennvorrichtung (optional)

VI-3

Metallformiat-Reaktor

VII-3

dritte Phasentrennvorrichtung

7

Strom enthaltend Raffinat (R2)

8

Strom enthaltend tertiäres Amin (A1); (Oberphase O3)

9

Strom enthaltend polares Lösungsmittel; Destillat (D1)

10

Strom enthaltend tertiäres Amin (A1) (Oberphase O2) und Ameisensäure-Amin-Addukt (A2) (Unterphase U2); Sumpfgemisch (S1)

10a

Strom enthaltend Unterphase (U2)

10b

Strom enthaltend Oberphase (O2)

11

Strom enthaltend tertiäres Amin (A1) (Oberphase O3) und Metallformiat, Wasser (Unterphase U3) und Ameisensäure-Amin-Addukt (A2) (mittlere Phase M3); Gemisch (MF)

12

Strom enthaltend Metallformiat, Wasser (Unterphase U3)

13

Strom enthaltend Metallhydroxid gelöst in Wasser

14

Strom enthaltend Ameisensäure-Amin-Addukt (A2) (mittlere Phase M3);

Fig. 1

I-1

hydrogenation reactor

II-1

first phase separation device

III-1

extraction unit

1

Stream containing carbon dioxide

2

Stream containing hydrogen

3

Stream containing formic acid-amine adduct (A2), complex catalyst, polar solvent, tertiary amine (A1); Hydrogenation mixture (H)

4

Stream containing tertiary amine (A1), complex catalyst; Upper phase (O1)

5

Stream containing formic acid-amine adduct (A2), polar solvent, residues of the complex catalyst; Subphase (U1)

6

Stream containing tertiary amine (A1), residues of the complex catalyst; Extract (E2)

7

Stream containing formic acid-amine adduct (A2), polar solvent; Raffinate (R2)

8th

Stream containing extractant (tertiary amine (A1))

9

Stream containing polar solvent

Fig. 2

IV-2

first distillation device

V-2

second phase separation device (optional)

VI-2

Metal formate reactor

VII-2

third phase separator

7

Stream containing raffinate (R2)

8th

Stream containing tertiary amine (A1); (Upper phase O3)

9

Stream containing polar solvent; Distillate (D1)

10

Stream containing tertiary amine (A1) (upper phase O2) and formic acid-amine adduct (A2) (lower phase U2); Swamp mixture (S1)

10a

Current containing lower phase (U2)

10b

Current containing upper phase (O2)

11

Stream containing tertiary amine (A1) (upper phase O3) and metal formate, water (lower phase U3); Mixture (MF)

12

Stream containing metal formate, water (lower phase U3)

13

Stream containing metal hydroxide dissolved in water

In Fig. 3, the reference numerals have the following meanings:

IV-3

first distillation device

V-3

second phase separation device (optional)

VI-3

Metal formate reactor

VII-3

third phase separator

7

Stream containing raffinate (R2)

8th

Stream containing tertiary amine (A1); (Upper phase O3)

9

Stream containing polar solvent; Distillate (D1)

10

Stream containing tertiary amine (A1) (upper phase O2) and formic acid-amine adduct (A2) (lower phase U2); Swamp mixture (S1)

10a

Current containing lower phase (U2)

10b

Current containing upper phase (O2)

11

Stream containing tertiary amine (A1) (upper phase O3) and metal formate, water (lower phase U3) and formic acid-amine adduct (A2) (middle phase M3); Mixture (MF)

12

Stream containing metal formate, water (lower phase U3)

13

Stream containing metal hydroxide dissolved in water

14

Stream containing formic acid-amine adduct (A2) (middle phase M3);

The embodiment according to 1 shows the preparation of the formic acid-amine adduct (A2). 1 describes the preparation of the formic acid-amine adduct (A2) according to steps (a1) and (a2) of the present invention. This will be a stream 1 containing carbon dioxide and a stream 2 containing hydrogen fed to a hydrogenation reactor I-1. If necessary, a stream 2a (not shown) containing polar solvent and a stream 4a (not shown), containing the tertiary amine (A1), the hydrogenation reactor I-1 are supplied to compensate for any losses occurring of the tertiary amine (A1) or the polar solvent. In addition, the hydrogenation reactor I-1 becomes a current 9 containing polar solvent and from the first distillation apparatus (IV-2 or IV 3 ; please refer 2 or 3 ) is returned.

In the hydrogenation reactor I-1, carbon dioxide and hydrogen are reacted in the presence of a tertiary amine (A1), a polar solvent and a complex catalyst containing at least one element selected from Groups 8, 9 and 10 of the Periodic Table. In this case, a hydrogenation mixture (H) is obtained which contains the complex catalyst, the polar solvent, the tertiary amine (A1) and the formic acid-amine adduct (A2).

The hydrogenation mixture (H) is called electricity 3 forwarded to the first phase separator II-1. In the first phase separation device II-1, the hydrogenation mixture (H) is subjected to phase separation to obtain a lower phase (U1) and an upper phase (O1). The lower phase (U1) contains the formic acid-amine adduct (A2), residues of the complex catalyst and the polar solvent and is used as stream 5 forwarded to the extraction unit III-1. The upper phase (O1) contains the tertiary amine (A1) and the complex catalyst and is called current 4 recycled to the hydrogenation reactor I-1.

Out of electricity 5 are in the extraction unit III-1 with electricity 8th containing a tertiary amine (A1) as extractant which extracts residues of the complex catalyst. The extractant used is a tertiary amine (A1) which is preferably selected from the third phase separation device (A1). 2 , VII-2, electricity 8th or 3 , VII-3, electricity 8th ) is returned.

In the extraction unit III-1, a raffinate (R2) and an extract (E2) are obtained. The extract (E2) contains the tertiary amine (A1) and the residues of the complex catalyst and is called current 6 recycled to the hydrogenation reactor I-1. The raffinate (R2) containing the formic acid-amine adduct (A2) and polar solvent is added as a stream 7 taken from the extraction unit III-1 and the step (b) fed (see 2 or 3 ).

In the embodiment according to 2 in the extraction unit III-1 (see 1 ) received electricity 7 containing the formic acid-amine adduct (A2) and the polar solvent (raffinate (R2)) fed to the first distillation unit IV-2. In the first distillation apparatus IV-2, the raffinate (R2) is separated into a distillate (D1) containing the polar solvent, which is used as stream 9 to the hydrogenation reactor I-1 (see 1 ) and into a biphasic bottoms mixture (S1).

The bottoms mixture (S1) contains an upper phase (O2) containing the tertiary amine (A1) and a lower phase (U2) containing the formic acid-amine adduct (A2). The sump mixture (S1) is called electricity 10 fed to the metal formate reactor VI-2. If necessary, the electricity 10 before being fed to the metal formate reactor VI-2 in the second phase separation device (V-2) in the upper phase (O2) and the lower phase (U2) are separated. In this case, the lower phase (U2) becomes current 10a fed to the metal formate reactor VI-2. The upper phase (O2) can be considered as electricity 10b to the hydrogenation reactor I-1 or the extraction unit III-1 in 1 be returned.

In the metal formate reactor VI-2, the formic acid-amine adduct (A2) present in the bottom mixture (S1) or optionally in the lower phase (U2) is dissolved with a metal hydroxide in water (stream 13 ) implemented.

In the metal formate reactor VI-2, a biphasic mixture (mixture (MF)) is formed containing an upper phase (O3) and a lower phase (U3). The upper phase (O3) contains the tertiary amine (A1). The lower phase (U3) contains the formed metal formate and water.

The biphasic mixture (mixture (MF)) is called electricity 11 the third phase separator VII-2 supplied and separated therein.

The lower phase (U3) becomes current from the third phase separator VII-2 12 discharged. The upper phase (O3) is called current 8th to the extraction unit III-1 (see 1 ) returned.

The embodiment according to 3 differs from the embodiment according to 2 in that in the metal formate reactor VI-3, a three-phase mixture (mixture (MF)) is formed, which as a stream 11 the third phase separator VII- 3 is supplied. The formic acid-amine adduct (A2) (middle phase M3) is used as stream 14 recycled to the metal formate reactor VI-3.

Examples

1. Thermal separation of the polar solvent

Examples 1 and 2 (separation of the polar solvent from the raffinate (R2))

Alcohol and water are distilled from the product phase (containing the formic acid-amine adduct (A2), and the polar solvent, raffinate (R2)) under reduced pressure by means of a rotary evaporator. A biphasic mixture is formed in the bottom (tertiary amine (A1) and formic acid-amine adducts (A2); bottom mixture (S1)). The two phases are separated. The composition of the distillate (containing most of the methanol and water, distillate (D1)), the upper phase (containing the free tertiary amine (A1), upper phase (O2)) and the lower phase (containing the formic acid-amine adduct (A2 Subphase (U2)) was determined by gas chromatography and by titration of formic acid against 0.1 N KOH in MeOH potentiometrically with a "Mettler Toledo DL50" titrator. Table 1 Example 1 (separation of the polar solvent) Example 2 (separation of the polar solvent) Feed mixture (% by weight) formic acid and trihexylamine in the form of the formic acid-amine adduct (A2) 199.8 g 8.9% formic acid 28.4% methanol 5.6% water 57.1% trihexylamine 199.8 g 7.8% formic acid 33.0% methanol 15.1% water 44.0% trihexylamine Formic acid: amine 1: 1.1 1: 1 print 200 mbar 200 mbar temperature 120 ° C 120 ° C Subphase (U2) in the bottom (S1) after distillation (% by weight) formic acid and trihexylamine in the form of the formic acid-amine adduct (A2) 79.8 g 22.1% formic acid 1.5% water 76.4% trihexylamine 69.4 g 14.9% formic acid 6.9% water 78.2% trihexylamine Upper phase (O2) in the bottom (S1) after distillation 50.5 g of 100% trihexylamine 32.7 g 99.7% trihexylamine 0.3% water Distillate (D1) 66.6 g 0.3% formic acid 81.2% methanol 18.5% water 93.1 g 70.1% methanol 29.9% water

Examples B1 and B2 show that various polar solvents can be separated off from the product phase under mild conditions in the process according to the invention, a lower (U2) formic acid and a lower phase (O2) containing predominantly the tertiary amine (A1) being obtained. The upper phase (O2) can be used for the extraction of the complex catalyst.

2. Preparation of Sodium, Potassium and Calcium Formate by Reaction of the Formic Acid-Amine Adduct (A2) with Sodium, Potassium or Calcium Hydroxide (Examples 3 to 7)

The formic acid-amine adduct (A2) is placed in a 250 ml flask with cooling and dropping funnel. Then 30 wt.% - Lye is slowly added dropwise with stirring (700 rev / min) and kept at 30 ° C and 70 ° C. After the respective reaction time, the liquid phases are separated from each other in a separating funnel and weighed. The composition of the phases was determined by ¹ H and ¹³ C NMR spectroscopy.

A biphasic product mixture was obtained in which the upper phase (O3) was enriched with free tertiary amine (A1), and the lower phase (U3) was enriched with water and the resulting sodium or potassium formate. Table 2.1 Example 3 Example 4 Tertiary amine (A1) 60.4 g of trihexylamine in the form of the formic acid-amine adduct (A2) 59.5 g of trihexylamine in the form of the formic acid-amine adduct (A2) formic acid 20.1 g of formic acid in the form of the formic acid-amine adduct (A2) 20.8 g of formic acid in the form of the formic acid-amine adduct (A2) lye 26.1 g of potassium hydroxide 75.0 g of water 18.8 g of sodium hydroxide 100.0 g of water Heat At 70 ° C At 70 ° C reaction time 6 hours 4 hours Mixture (MF) 58.8 g Upper phase (O3) 100.0% trihexylamine 51.4 g upper phase (O3) 100.0% trihexylamine 7.8 g middle phase (M3) formic acid-amine adduct (A2) (4.5: 1 trihexylamine: formic acid) 122.6 g lower phase (U3) 29.2% potassium formate 70.8% water 127.3 g lower phase (U3) 20.6% sodium formate 1.1% sodium hydroxide 78.3% water Formic acid conversion, the formic acid contained in the formic acid-amine adduct (A2) 100.0% 92.0% Table 2.2 Example 5 Example 6 Example 7 Tertiary amine (A1) 59.5 g of trihexylamine in the form of the formic acid-amine adduct 59.5 g of trihexylaminine form of the formic acid-amine adduct 59.5 g of trihexylamine in the form of the formic acid-amine adduct formic acid 20.8 g of formic acid in the form of the formic acid-amine adduct 20.8 g of formic acid in the form of the formic acid-amine adduct 20.8 g of formic acid in the form of the formic acid-amine adduct lye 18.8 g of sodium hydroxide 80.0 g of water 25.2 g of potassium hydroxide 80.0 g of water 17.7 g of calcium hydroxide 80.0 g of water Heat At 100 ° C At 100 ° C At 100 ° C reaction time 4 hours 4 hours 4 hours Mixture (MF) 58.7 g upper phase (O3) 100.0% trihexylamine 115.8 g lower phase (U3) 25.9% sodium formate 74.1% water 58.5 g upper phase (O3) 100.0% trihexylamine 126.1 g lower phase (U3) 30.1% potassium formate 69.9% water 58.2 g upper phase (O3) 100.0% trihexylamine 91.2 g lower phase (U3) 19.7% calcium formate 80.2% water Formic acid conversion, the formic acid contained in the formic acid-amine adduct (A2) 100.0% 100.0% 99.9%

Examples 3 to 7 show that high sales are achieved. The studied systems formed separable phases, with the upper phase (O3) containing the free tertiary amine (A1) and the lower phase (U3) sodium, potassium, or calcium formate as an aqueous solution.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Industrial Organic Chemistry, Hans-Juergen Arpe, WILEY-VCH Verlag GMBH & Co. KGaA, Weinheim 2007; ISBN 978-3-527-31540-6, pages 48 and 232-235 [0002]
• Chem. Rev. 1995, 95, 259-272 [0004]
• KD Henkel, "Reactor Types and their Industrial Applications," in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH Verlag GmbH & Co. KGaA, DOI: 10.1002 / 14356007.b04_087, Chapter 3.3 "Reactors for gas-liquid reactions" [0065]
• E. Muller et al., "Liquid-liquid Extraction", in Ullman's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH Verlag GmbH & Co. KGaA, DOI: 10.1002 / 14356007.b93_06, Chapter 3 "Apparatus" [0081]
• E. Müller et. Al., Liquid Liquid Extraction, in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH Verlag GmbH & Co. KGaA, DOI: 10.1002 / 14356007.b03_06, Chapter 3 "Apparatus" [0131]
• KD Henkel, "Reactor Types and their Industrial Applications" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH Verlag, Chapter 3.3 [0141]

Claims (15)

Process for the preparation of at least one metal formate selected from the group consisting of sodium formate, potassium formate, magnesium formate, calcium formate and aluminum formate comprising the steps of (a) providing a formic acid-amine adduct of the general formula (A2) NR ¹ R ² R ³ * x _i HCOOH (A2), in which x _{i is} in the range of 0.4 to 5 and R ¹ , R ² , R ³ independently represent an unbranched or branched, acyclic or cyclic, aliphatic, araliphatic or aromatic radical each having 1 to 16 carbon atoms, wherein individual carbon atoms independently of one another may also be substituted by a hetero group selected from the groups -O- and> N- and two or all three radicals may also be linked together to form a chain comprising at least four atoms, and (b) reacting the formic acid amine Adduct (A2) in the presence of water with at least one metal hydroxide selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and aluminum hydroxide to obtain an at least biphasic mixture (MF) containing an upper phase (O3) containing the corresponding tertiary amine of general formula (A1) NR ¹ R ² R ³ (A1), in which R ¹ , R ² , R ^{3 have} the meanings given above, and a lower phase (U3) containing the corresponding at least one metal formate and water. The process of claim 1 wherein the providing of the formic acid amine adduct (A2) of step (a) is by homogeneously catalyzed reacting carbon dioxide with hydrogen in the presence of a tertiary amine (A1) and at least one polar solvent selected from the group consisting of Methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol and water. The process according to claim 1 or 2, wherein the reaction in step (b) is carried out at a temperature in the range of 20 to 200 ° C and a pressure in the range of 0.01 to 10 MPa. The process according to any one of claims 1 to 3, wherein the at least one metal hydroxide is added to the step (b) as an aqueous solution containing 5 to 50% by weight of metal hydroxide based on the total weight of the aqueous solution. A process according to any one of claims 1 to 4, wherein the preparation of the formic acid-amine adduct (A2) comprises the following steps: (a1) homogeneously catalyzed reaction of a reaction mixture (Rg) comprising carbon dioxide, hydrogen, at least one polar solvent selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol and water and a tertiary amine (A1) of the general formula NR ¹ R ² R ³ (A1), in which R ¹ , R ² , R ^{3 have} the abovementioned meanings, in the presence of at least one complex catalyst which contains at least one element selected from groups 8, 9 and 10 of the Periodic Table, in a hydrogenation reactor to obtain, optionally after addition of water , a biphasic hydrogenation mixture (H) containing an upper phase (O1) containing the at least one complex catalyst and the tertiary amine (A1), and a lower phase (U1) comprising the at least one polar solvent, residues of the at least one complex catalyst and formic acid Amine-adduct (A2) contains, NR ¹ R ² R ³ * x _i HCOOH (A2), (a2) phase separation of the hydrogenation mixture (H) obtained in step (a1) in a first phase separation device into the upper phase (O1) and the lower phase (U1) and extraction of the radicals of the at least one Complex catalyst from the lower phase (U1) in an extraction unit with an extractant containing the tertiary amine (A1) to obtain a raffinate (R2) containing the formic acid-amine adduct (A2) and the at least one polar solvent and an extract (E2) containing the tertiary amine (A1) and the residues of the at least one complex catalyst, and the formic acid-amine adduct (A2) contained in the raffinate (R2) according to step (b) is reacted. Process according to claim 5, wherein the upper phase (O1) is recycled to the hydrogenation reactor. Process according to claim 5 or 6, wherein the extract (E2) is recycled to the hydrogenation reactor. A process according to any one of claims 5 to 7, wherein the extractant used is the tertiary amine (A1) obtained according to step (b). A method according to any one of claims 5 to 8, wherein the reaction of the raffinate (R2) according to step (b) comprises the following steps (ba) separating the at least one polar solvent from the raffinate (R2) in a first distillation apparatus to obtain a distillate (D1) containing the at least one polar solvent which is recycled to the hydrogenation reactor in step (a1), and a biphasic bottoms mixture (S1) containing an upper phase (O2) containing the tertiary amine (A1) and a lower phase (U2) containing the formic acid-amine adduct (A2), (bb) if appropriate working up of the bottom mixture (S1) obtained in step (ba) by phase separation in a second phase separation device into the upper phase (O2) and the lower phase (U2), (bc) reacting the formic acid-amine adduct (A2) present in the bottom mixture (S1) or optionally in the bottom phase (U2) in the presence of water with a metal hydroxide selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and aluminum hydroxide a metal formate reactor to obtain an at least two-phase mixture (MF) containing an upper phase (O3) containing the corresponding tertiary amine (A1), and a lower phase (U3) containing the metal formate and water. A process according to any one of claims 1 to 9, wherein the mixture (MF) obtained according to step (b) is separated into the lower phase (U3) and the upper phase (O3) in a third phase separation device. The process according to claims 1 to 10, wherein the upper phase (O3) in step (a) is used for the preparation of the formic acid-amine adduct (A2). Method according to one of claims 5 to 11, wherein the upper phase (O3) is recycled to the extraction unit and used there as an extraction agent. A process according to any one of claims 5 to 11, wherein the upper phase (O3) is recycled to the hydrogenation reactor. A method according to any one of claims 2 to 13, wherein as the tertiary amine (A1) an amine selected from the group consisting of tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine and tri-n-octylamine is used. A process according to any one of claims 2 to 14, wherein the polar solvent used is water, methanol or a mixture of water and methanol.

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